In a JStyledDocument setting the logical style on a paragraph causes the CharacterStyle of the Style to be set on the next paragraph of the range not the paragraph in the range.

To illustrate the problem, add the following line as the first definition in
Paragraph[] data

new Paragraph ("normal", new Run[] {
new Run("none", "Stupid little Test"),
}),

In the display you'll notice that the Title will set with the CharacterStyle that is in normal.